CA1208436A - Coal-aqueous mixtures having a particular coal particle size distribution - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Coal-aqueous mixtures comprising coal having a speci-fied particle size distribution are disclosed herein.

Description

lZ~8436 1 CO~L-~QV~OUS MI.YTURES ~ VI~G A P~RTICUL~R
CO-~L Pi~RTICLE SIZ_ DIST~T3UTION

The present invention relates to the dispersion of carbonaceous materials and more particularly to coal-aqueous coal mixtures.
Coal as an energy source is in abundant supply.
I~ is estimated that in the United Sta-tes there is more energy available in coal than in petroleum, natural gas, oil shale and tar sands combined. The substitution of coal for natural gas and oil on a large scale would therefore seem a ready-made solution to our energy pro-blems. Unfortunately, however, unlike oil and gas con-sumption, coal use is limited not by reserves or produc-- 15 tion capacity but rather by the extraordinary industrial and regulatory difficulties of burning it in a convenient, efficient and environmentally acceptable manner.
A number of techniques are being explored to provide coal as a more useful energy source. One such technique employs ~asification methods such as destructive distillation, to effect the conversion of coal to a low or medium Btu gas. In another approach, high pressure h~7drogenation is utilized to liquefy coal to make it more suited for transport, burning and the like.

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~)8436 1 Another t~c~nique suggested, and the one to ~hich the prcsent invention rclates, is the technique whereby solid coal p~rticles are dispersed in a fluid carrier medium, such as fuel oil or water to form coal-5 aqueous or coal-oil mi:~t~res.
Coal-oil and coal-~queous mi~tures, however, are distinct systcms, each having its o~Jn difficulties of formulation. For example, while coal and oil are relatively compatible,coal and water are not. Thus, 10 unlike in the formulation of coal-oil admixutres, in the formulation of coal-aqueous admixtures, the initial dispersing of the coal in the continuous water phase, especially large amounts of coal, represents a challenging obstacle. ~oreover, after dispersion, stabilizing,i.e.
15 ~eeping the coal from settling out of the watex phase, must be also achieved.
Such coal mixtures offer considerable advantages.
They are more readily transported then dry solid coal, are more easily stored and are less subject to the risks 20 of explosion by spontaneous ignition, the latter being a significant factor in handling coal. In addition, providing coal in a fluid form can permit its burning in apparatus normally used for burning fuel oil. This can greatly facilitate the transition from fuel oil to 25 coal as a primary energy source, another highly desirable result.
Various coal-oil and coal-aqueous mixtures have been described in the literature. For ~ample, British Pa~ent No. 1,523,193 discloses a mi~ture comprised of 30 fuel oil and from 15 to 55% by weight of finely ground ~ coal particles reduced in partic~e slze to 10 microns or -lZU8~36 1 finer. The use of ~uel oil as a carrier medi~ neg2tes the requirement of lessening our dependence upon fuel Qil .
In United States Patent No. 3,762,~87, thcre is disclosed a dispersion of coal in an aqueous medi~m ~herein the coal is ground to a defined array of parti-cle sizes, a substantial portion of which being about 325 mesh Tyler Standard screen or even finer.
The article tit-led "~evelopment and Evaluation 10 of ~Iighly-J~oaded Coal Slurries" published in the 2nd Inter-national_Symposium on Coal-Oil Mixture Combustion, November 27-29, 1979, teaches coal-aqueous mixtures using coal of bimodal particle size distributions and contain-ing modified starches, biocides and a wetting agent such 15 as TRITON X, an octylphenoxy (ethyleneoxy) ethanol sur-factant of low molecular weight.
British patent application GB 2 099 451A dis-closes aqueous coal suspensions which contain two separate groups of coal particles, the particles of the 20 first group having an average size of from 210 to 6Q ~m, the maximum size not exceeding 300 ~m and the particles of the second group having an averaye size of from 1/6 to 1/20 of the average size of the partices of the first groupO
While the art has attempted to provide coal in dispersed fluid form, as evidenced by the above-described procedures, there still remains the need for improving these ~ethods in order to provide higher solids and more s~able coal mixtures. It would be highly desira-30 ble to pxovide coal in a~ueous mixture form wherein only minor amounts of additive materials are needed to disperse :.

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1 the coal to high solids conc~ntrations of 70% by wei~ht, or higher. It ~.~ould be further desir~hle to provide coal-aqueous mi:;tures whercinthe coal is precleaned of impurities so that the resultant mixtures are clean burning or relatively clean burning and thus more cnvironmentally acccptable.
The pre~ent invention relates to a stabilized, high solids content coal-aqueous mixture comprisiny particulate coal as a dispersed solid material; water as a carrier medium; and a polyal~yleneoxide nonionic surfactant having a hydrophobic portion and a hydrophilic portion, said hydrophilic portion comprising at least about 100 units of e~hylene oxide, wherein said particulate coal has the following particulate size distribution:

% weight based on mesh (Tyler Standard screen size) total dry coal -60, ~10;0 5--20 -100,+~00 15-30 -200,+325 15-30 U.S. Serial No. 230,062 filed January 29, 1981 (now U.S. Patent No. 4,358,293) discloses the surprising discovery that certain polyal~yleneoxide nonionic surfactants are excellent additives ~or forming coal-aqueous mixtures having high coal solids concentrations. It is also disclosed therein .

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~8436 1 that polyalkylencoxide nonionic sur~actants of high molecular weight having a hydrophobic portion and a hydrophilic portion, the h~drophilic portion being comprised o~ at least about 100 ethylene oxide repeat-ing units, provide coal-water dispersions having very high coal solids concentrations of about 70~ by weiyht coal, or higher, when the surfactant is present in an amount sufficient to disperse the particulate coal in water. The resultant mixtures are free-flowing and are adapted to provide coal in a form ready for trans-port, storate and clean-burning. Surprisingly, the surfactants employed can differ in chemical structure so long as they are of the selected type r are of suf-ficient molecular weight and are comprised of at least about 100 units of ethylene oxide.
It has now been surprisingly discovered that by increasing the content of the coarse fraction of coal particles, in the preparation of the coal-aqueous slurries disclosed in the afore-mentioned U.S. applica-tion Serial No. 230rO62, (now U.S. Paten~ No. 4,358,293)even more improved coal-aqueous slurries are provided.
For example, the coal slurries prepared in accordance with the present invention are characterized by even higher solids content, excellent long term storage sta-bility and other advantages which will become apparenthereinafter.
The coal-aqueous slurries of the present inven-tion are comprised of coal or other carbonaceous particu-late material as the dispersed solid; water as the 3 carrier medium; and a polyal~yleneoxide nonionic sur-factant, as further described herein.

~Z~:t8~36 1 ~s used herein "polyalkyleneoxide nonioni~
surfactant" connotes all compositions, compounds, m~'Y.-tures, polymers, e~c. havin~ in part an alkylene o~: de repeating unit of the structure:

~f ~ t and having a hydrophobic portion ~nd a hydrophilic por-tion and which does not dissociate or ionize in solution.
10 These surfactants have a polymeric portion comprise~ of repeating units of eth~lene o~ide of the general for.~ula:

--C -- - C
\ /
O

Moreover~ the polyalkyleneo~ide nonionic surfactant compos~tions:employed in this invention are of high molecular weight, i.e., from about 4,000 or higher, depending on the particular surfac~ant e~ployed, are hydrophilic and are comprised of at least about 100 repeating units of the ethylene oxide. In addi-tion, the surfactants utilized have a hydrophobic portionand a hydrophilic portion and are nonionic. Being nonionic, these compositions are generally not subject to ionization in aqueous solutions of acid or al};ali.
Suitable hydrophilic polyalkyleneo~ide nonionic sur'actants for use in this invention are the commercially available glycol ethers of alkyl phenols of the follo~1ing ~eneral formula I:

~ 2 2 )n Cll2 C1l2 0~1 ` ~ _7_ ~2~43~

1 ~herein R is substituted or~lsu~stituted al.:~l of Cro~
1 to 18 carborl atoms, prefer2blv 9 carbo-l ato~s; sub-stituted or unsubstituted ar~l, or an ar,lino ~rou~ and n is an integer of at least about 100.
These nonionic surfact~nts are available in a h~ldc array of molecular ~eicJIIts c~ elltlin~ ~rimarily on the value of "n", i.e., the num~cr of ethylene o::ide repeating units. Surprisingly, it has been found that these surfactants of a high molecular weight of about 4,000 or higher wherein "n" is at least 100, or higher are particularly effective as dispersants for forming coal-aqueous mixtures to high coal solids concentration requiring little if any further additives, etc., to form highly flowable liquids.
Procedurcs for the preparaticnof the glycol ethers of formula I are well ~nown and are described, for example, in ~nited States Patents ~los. 2,213,477 and 2,496,582, ~ Generally, the production of these compo-sitions involves the addition of substituted phenols .ith molar porportions of ethylene o:.ide monomer.
Thus, polyalkyleneoxide nonionic surfactants suitable for use in the invention include the glycol ethers f al};ylat~d phenols having a molecular weight o~ at least about 4,000 of the general formula:

R - ~ 0 -(CEl2CEl20)n-CE~2-CEI2--OH

3o .herein R is substituted or unsubstituted al~yl of from 1 to 18 carbon atoms, preferably 9 carbon atoms; sub-stituted or unsubstituted arvl, or an amino sroup, and 1201~36 " --8--1 n is an integer of at le~st about 100. The substituen,s of the alk~1 and arvl radicals can include halo~en, hj~.-oi:;, and the like.
Other suitable ~onionic surractants are the poly(o~yethylene)-pol~.~(o~propylene)-polï(o:yethylene) or, as othcrwise ~scribcd, p~o?o~:ylated, ctho~ylated propylene gl~col nonionic surfactant block pol~mers having a molecu-lar weight of at least about 6,000 of the general formula:

Ho(cH2cH2o)a[cH(cll3)cH2o]b(cH2c~2o)c wherin a, b and c are whole integers and wherein a and c total at least about 100.
. 15 Still other polyalkyleneoxidc nonionic surfac-~ants suitable for use in the invention are the block polymers of ethylene and propylene oxide derived from nitrogen-containing compositions such as ethylene diamine and having a mol~cular weight of at least about 14,000 of the general formula:

H(C2H4Oje( R2)a (R2O~)C(C2H4O)gH

N-Rl-N

,,,,,, / \
H(C2H4O)f~t R2)b (R2o-)dtC~H4o)hH

12~436`

~herein ~1 is an al};ylene radical having ~ to 5 carbon atoms,prefer~bly 2: P~2 is al~;ylene radic~l having 3 to 5 carbon atoms, prefer~bly 3; a, b, c, d, e, f, g and h are ~holc integcrs; and e, f, g and h total at least abou~ l00.
The coal-aqucous mi~ture compositions of the invention herein ~re charactcrizcd by hav.~ng a hig}~ coal content and a relatively low viscosity of about 2,000 or 10 lower.to in excess of-6,000 centipoise (cP) e.g. as measur~d in a Brookfield viscometer, model "RVT, fitted with a number 3 spindle, at l00 r p.m. even at solids levels of 70~ by weight, or higher, based on the total weight of the mix-~ure. These compositions can also include a~ounts of con-ventio~al flow modifying materials,such as thic~eners, 15 glues, defoaming ~gents, salts, e~c., depending upon the use intended.
The products of the invention contain only minox amounts of surfactant additives in the order of about 0.l to 3.0 percent by iweight. They further contain particulate coal as the dispersed solid in an amount from about 45 to 80 percent; water as the carrier medium in an amount of from about l9.9 to 52 percent and, if desired, rrom about 0.l to 2 percent of a thickener or thic~eners; about 0.0l to 2 percent of a defoaming ~gent and about 0.l to 2 per-25 cen~ of salts, anti-bacterial agents,caustic or other additive flow control agents, all of the percentages given being based on the total weight of the mixture.
The most preferred glycol ethers of the tvpe generally describe in formula I are the nonylphenoxy 3 (polyethyleneoxy) ethanol compositions of the formula:

. CgHlg ~ 2 2 )n CH2 C~12 OH

.. .

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hercin n is about 100 or hisil~r.
Commerciall~ available surfactants of t!~is t~e ~re su~plicd by thc GAF Cor?oration under the dcsignat ons IGEPAL C0-9~0 and IGEP,~L C0-997. .. Othcr commcrcially 5 available surfactants o~ this tlDe are su??lied by tne l`hom~son-~la~w2rd Cllcmical Co. under thc dcsi~nation T-Det ~!-100, and ~hitestone Cl~emical Co. under the designation ICO~lOL ~P-100.
As stated hereinbefore, another gro~p of pol~-lO all;yleneo~:ide~nonionic surfactants use ul in ~he inven-,ion are the well ~;no~n pol~(o.:yethylene)-poly(oxypro-?~lene)-poly(oxyethylene) nonionic surfactant block poly-mers. These surfactants comprise the block polymers of ethylene oxide and propylene o~ide with the repeating units of propylene oxide constituting the hydrophobic portion of the surfactant, and the repeating units of ethylene oxide constituting the hydrophilic portion of the surfactant. These bloc~ polymer compositions are of the general formula II:
~0 ( 2cH2o)a[cHlcH3)cH2o]b(cH~cH~o) ~ II

~herein a, b and c are wllole inteqers an~ wherein a and c total at least about 100.
These compositions can be prepared, and are commercially available, in a variety of molecular weights, depending primarily on the number of repeating units of propylene and ethylene o~ide. It has been found that these block polymers having a molecular weight of at least about 6,000 and comprising at least about 100 -e?eating units of ethylene o~ide are e~cellent additives for dispersing coal in a water carrier to the desired .

~5 ~Z0~3436 1 hish coal solids concentrations o~ about 4; to 80 percent, preferabl~- about 70 percent coal particles, based on the weisht of the total ~i~:ture. Thus,~:ith rcference to tl~e above formula II, tlle ~ol,(o~ etilvlc:lc)-?ol~(o~:vprop-lcne)-pol~ (o~ eth~lene) nonionic surfactants suitable for usein the invcntion are tllos~ t.herein a, l~ an~ c are integers and a and c total abo~t 100 or hi~her.
Suitable procedures for the prod.uction of the block polymers of ~ormula II are described in the patent literature in, for e~:ample, Uni~ed States Patents Nos.

2,674,619; 2,677,700 and 3,101,374, Generally, these block polymers are prepared~
b~ a controlled addition of propylene oxide to the t~;~o dro~yl cJroups of propylene ~lycol to form the hydro-,hobe, followed by the controlled addition of ethylene o:ide to "sandwich" in the hydrophobe between the two hvdrophilic polyeth~leneo~ide ~roups The nonionic surfactants of this tvpe (Formula II) having the requisite n-~mber o~ at least 100 units of e.h~lene oxide are available from the BASF-~yandotte Corporation under the PLURONIC designation, Ceries Nos.
F-77, F-87, F-68, F-88, F-127, F-98, and F-108. These comDositions hav~ at least 100 ethylene o~ide units, 5 as per the followin~ table of these PLURONIC surfactants:

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E~h~lene ~m~cr o_ E~h~lenc RO`;IC F~to'. ~t. O~:ldeC:rid- ~'ni~s F-77 6,600 70 105 F-87 7, 700 70 120 F-G8 8, 350 80 151 F-88 10, 800 80 195 F-12712, S00 70 200 F-98 13,000 80 235 F-1081-'1, 000 80 255 As also described hereinbefore, a further grouD
of polyalk~yleneoxide nonionic surfactants suitable as coal dispersants herein.are the nitro~en containing block ?oly-~.ers of ~he general formula III
H(C2H40)e( R2)a (R20-~C(C2HgO)gH

N-Rl-N

H(C2H40)f( -`.R2)b (R20-)d(C2H40)h 3o ....
. ~ .

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1 ~hcrein Rl is an alkylene radical having 2 to 5 c2rbon a~oms, prefcr~bly 2; 1~ is an al}:ylcne radical ha~ing 3 to S carbon atoms, plefcra~ly 3; a, b, c, d, e, f, 9 and h are ~.hole intec3ers; an~ e, f, g and h total at 5 le2st about 100.
These matcrials are 2re~ar~d by ~Lhe addition o~ a C3 to C5 alkylene oxide to an alkylene di~mine under conditions to a~d tt~o polyo~yal};ylene groups to each of - the nitrogen groups in the presence of a catalyst so as lO to polvmerize the o~yalkylene groups into the desired long-chained polyo~yal~ylene radicals. After the desired addition and polymerization of the C3 to C5 alkylene oxide group has been completed, ethylene oxide is introduced and is added to the polyo~alkylene groups to mpart the 15 desired hydrophilic characteristics to thP compound.
The preparation of these materials from commercially available alkylene diamines and al~ylene oxides is kno~n in the art.
In general, the agents are pre~ared by mixing 20 the C3 to C5 alkylene o~:ide ~-ith the alkylene diamine at atmospheric or elevated pressures~ at temperatures between about 50 to 150 centigrade and in the presence of an alkaline catalyst such as an al~ali metal h~dro~ide or alcoholate. The de~ree of polymerization or the size of the hydrophobic group is controlled by the relative proportions o C3 to C5 al~ylene o~:ide and alkylene dia-~ine, the alkylene oxide being introduced in a sufficient ~uantity to obtain a hydrophobic base weight of about 2000 to 3600 units although other weights can be provided.
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1 These sur~actants (Formula III) having the requisite number of at least 100 ethylene o~ide repeat-ing units are available from the ~SF l'yandotte Chemicals Corporation under the TETRONIC desi~nations Series ~os.
5 1107; 1307; 908 and 1508. These compositions have at least 100 ethylenc o:;ide units, as per the following table of these T~TRONIC surfactants.

% Ethylene Number of Ethylene lO T~T~ONIC ~iol. ~t. O~ide ___ O~ide Re~cating Units 110714,500 70 230 130715,500 70 245 908 16,500 80 300 150817,000 80 309 In accordance with the present invention, it has now been surprisingly discovered that by increasing 20 the content of the coarse fraction (-60 to +100 mesh) of the coal particles used to make-up the coal slurry, higher solids content are achieved. Thus, in accordance with the invention herein it has been found that the following size consist, i.e., coal p~xticle size distribution 25 will provide higher solids slurries at improved fluidity:
~ by wei~ht of dry mesh (Tvler Standard screen size) coal ~article blend .... . . . _ _ -60, ~100 5-20 -100,~200 15-30 -200,+325 15-30 ..

1~08436 1 A preferrcd coal particle distribution in accordance with tl-e present invention is as follo~ts:
bv weight of coal ~esh (Tyler Standard screen size) Darticle blend _ -60, +100 1S-20 -100,-~200 . ~0-25 -200,+32S 20-25 -325 . 30-q0 By the above designations, for example ~60, +100 is meant that the particles in this fraction pass through 60 mesh screen size but not through 100 mesh screen size; thus -100, +200 means the particles in this fraction pass through 100 mesh screen size but not throu~h 200 mesh screen size; -200, +325, the ~articles in this fraction pass through 200 mesh screen size but not 325; -325, all these particles pass through 325 mesh.
Thus, particles in the fraction -60, +100 range in sizes from about 149 microns to greater than about 250 microns; the particles in the fraction -100, *200, range in size from akout 74 microns to less than a~out 149 microns; in the fraction -200, ~325,the particles range in size from 44 microns to less than about 74 microns; -325 fraction the particles are less than 44 microns.
Any of a wide array of coals can be used to Iorm the coal-aqueous mixtures of ~he invention, includ~
ing anthracite, bituminous, sub~bituminous, mine tail-ings, fines, lign.ite and khe li~e. Other finely divided ~8~

1 solid carbonaceous matexials ma~ also be used, e.g., coke, pre2ared either from coal or from petroleum.
To form the coal-aqueous ~i.:tures, coal is pulverized by conventional procedures and the appro-5 priate particle distribut;on is acllieved by the useof U.S. mesh sieves an~ blell~in~ the various fractions.
Advanta~eously, according to the invention, the untreated pulverized raw coal, has been beneficiat~d, i.e., clea~ed of amounts of ash and sulfur. The art 10 will appreciate that mixtures formed of beneficiated coal offer considerable advantage. They are clean burn-ing or relatively clean burning, and are more suited for burning in apparatus for powering utilities, home burners and the like without undue burdensome and expen-15 sive cleaning apparatus.
Any of a wide array o~ beneficiating treatmentscan be employed in preparin~ the particulate coals, includ-ing conventional heavy-media separations, magnetic separa-tion and the like. The preferred method for providing 20 the beneficiated coal particles is b~ a chemical treat-ment process such as described in U.S. Patent No. 4,304,573.
Generally, according to the preferred chemical beneficiation treatment method, raw as-mined coal is ground in t~e presence of water to the desired particle 25 sizes. The ground coal is treated in an aqueous medium with a monomeric compound, generally an unsaturated polymerizable composition such as readi~y available tall oil fatty acids in the presence of a metal initiator such as cupric nitrate; and minor amounts of fuel oil, all in 30 an aqueous phase are also present. The ground coal so treated is made hydrophobic and oleophilic and is separated from the unwanted ash and sulfur by a froth flotation technique.

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~f ~LZ(~1~436 1 The cleaned coal recovered from the preferred chemical treatmellt process, now in the form of bene~ici-ated coal p~rticles, is suited for the coal-aqueous mi~:tures of the in~ention. These coal particles are char~cterized by having an ash content reduced to levels of about 0.5 to 6.0nO and a sulfur content reduced to levels of about 0.5 to 2.0~.
As in said U.S. Serial No. 230,062, filed January 29, 1981, (now U.S. Patent No. 4,358,293)), it is preferred herein to form the coal-aqueous mixtures by first adding the surfactant to water together with other additives such as conventional defoaming agents, if desired~ This admixing can be done with stirring at conditions of atmospheric or nearly atmospheric temperature and pressure, Thereafter, the particulate coal, preferably beneficiated coal particles, is added to the mi~ture to produce a coal-aqueous mixture of high coal solids content of about 45 to 80~ by weight coal, based on the total weight of the mixture at atmospheric or nearly atmospheric temperatures and pressures. If desired, thickeners can then be added to further stabilize the mixture to assist in preventing the coal particles from settling when the mixture is to be stored for extended periods. Caustic soda or other bases can also be added at this point. As will be apparent, adding thickeners in or n~ar the final stage is preferred so that the stirring requirements are kept at a minimum.
The coal-aqueous mixtures can be prepared in a batch operation or in the continuous mode. In continuous pro-duction, the coal can be admixed with water in a first . .

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l stage along ~Jith other flow control agents such as the surfacta~t. The compositions oE the first sta~e can thcn be transferred continuously to a second stage whcrein the thic~ener is added. Again, adding the thickener at - 5 the later stage results in reduced stirrin~ requirements.
The ooal a~ucou~ may be prcparcd by first adding surfactant and other additives, such as conventional defoaming agent, if desired, to water and mixing, under low speed agitation conditions, such as at from about 10 500 rpm to about 1500 rpm, preferably about lOOOrpm, for a time of from about 30 seconds to about 3 minutes, prererably about l minute. Thereafter, ~he particulate coal, preferably beneficia-ted coal particles in the par-ticle size distribution of the present invention, is added to the mixture and admixed ther,ein under moderate or medium agitation condi~ions, for example, at an rpm ln the range of from about lOOOrpm to about 3000 rpm, preferably about 2000 rpm for a time sufficient to provide a wetted out admi~ture. Usually this time is in the range of from about 5 minutes to about 20 minutes.
At this time, the agitation of the admixture is increased to a high speed, for example, from above about 3003 rpm to about 6000 rpm, preferably about 4000 rpm for a time sufficient to ~isperse the coal, usually from about 5 minutes to about 15 minutes, preerably about lO minutes.
I~ desired, thickeners are then added to the slurry under the afore-described high speed agitation conditions, e.g.
4000 rpm, for a further time of from about l minutes to ~ - 19- ~
lZ~343~

1 about 3 minutes, preferably about 2 minutes. In the preparation of a most preferred formulation, other ingredients, such as viscosity stabilizers and anti-bacterial agents are then added to the formulation at high speed agitation for a further time of from a~out 1 minutc to about 3 minutos, pre~cra~ly about 2 minutes.
By wetted out or wet as used herein, it is meant that the surface of each coal p~rticle is covered with ~ater.
Typical ~ixing or dispersing apparatus employed herein incluae for example Premier Mill Co.'s Hi-Vispersa-tor High-Speed Disperser.
As indicated above, additiv~s that can be added to the coal-aqueous mixture include defoaming agents, thickeners, salt5 ~ b~ses, other flow modifying agent and combinations of these materials.
Generally, the defoaming agents that can be used are conventional and include both silicon and non-silicon containing compositions. A commercially avail-able defoaming agent suitable for use in the mixtures is COLLOID 691, supplied by Colloidsl Inc. This compo-sition generally comprises a mixture containing mineral oil, amide and an ester.
Thickeners can also be added to the mixture.
They are added to increase the non-settling characteris-tics of the composition Suitable thic~eners include,for example, xa~than ~um, guar gum, glue and the like.
Othex thickeners include, ~or example, alkali soluble acrylic polymers te.~. ~CRYSOL ICS-l sold by Rohm and Haas Company). Combinations of these ~hickeners are also contempIated herein. For the purposes herein, the thickeners are generally used in amounts ranging from about 0.01 to about 3.0~ by weight, based on the total weight of the mixture.

* Trade Mark i`~l ~ ' 843~

l In preparing the compositions containing the preferred 70% to 74~ by weight coal, based on the weight of the total mi~ture, the polyalkyleneoxi.de nonionic surfactants are preferably mi~ed with water in a propor-5 tion of about-0.3 part by weight surfactan-t to 29.3 parts by wciyht, w~ter at atmospl~cric or ncarly ~tmosphcric temperatures and pressures. A defoaming agent is also added to the water in an amount of about 0.03, part by weight, to assist in processing. The pulverized coal lO (in the particle size distribution disclosed hereinbefore) is then mixed with the water in a proportion of 70 parts by weight coal to 29.3 parts by weight of water to obtain a flowable liquid. If desired, to the mixture can then be added about 0.12 to about 0.15, part by weight, of 15 thickener or thickeners to provide protection against settling. Other additives such as salts or bases, anti-bacterial agents such as formaldehyde, and the like, viscosity stabilizers, such as ammonia, etc. can also be added in about 0.2 to about 0.3, part by weight, of the 20 total mixture to further assist in dispersing the coal and providing ~he other obvious advantages.
It is also contemplated herein to utilize a combined suractant, namely the afore-disclosed non-ionic surfactants and a polyelectrolyte surfactant such 25 as an oligomeric anionic polyacrylate surfactan~.
~ he following E~amples will urther illustrate the invention:

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- 2 1 - ~a2~843t~

~ V~ " o o C ~ o ~ C .`

~n ~, oo o o o ,oO o . C C

~ o V~ V~ o . o o o ,o~ oO o o ~ 5~
_ ~ o v ,. .7 ~ o ~

I . ~ V~ ~ o o VOO~ ~ o U~ ~ o o ~ r~ ~ ~ ~o ~ ~ ~ , ~

1 `v o m o . O o o' o o v~ o o _ ~ ~ V N V O v ~ ~n `D O a:l O ~

¦ V V O o ~ ~ ~ VO ~ O O O O

l _ ~ ~ v~ ~ v~ D v~ o ~ o ~ o o ~L~ O ~ u~ O O o O O O o o o o 20 5~1 _~o~ Uv, ~v~ ~OD ~` a ~oo ~o V~ o v~ r~ O ~ r O

~ ~ ~ V~ O ~D 0 0 O

In O V O N O ~o N o _~ o 1~ o ~ o o O V~ V~ O O ~ O O o O o o ~ ~ v ~ O ~ o n o ~ -1 o O ~o~ o o o o o ... ,, , , ~oo~
z~ + I v~ 0 o o ,.~ o ~ _ o o g o o O _ N . ~ j~ 8 ~ ~ a 8 ' 8 ~ 8 ~ 8 1 Each of the Exam~les in the Table contain the 'ollowlng ingredients:
Ingredient rlaterial Parts by ~eight 1 Water from about 25 to abcut 29 (adjust~d according to coal content) 2 Tctronic 1307 from about .39 to ~ ut .36 3 Colloid 691 .03

4 ~ Cleancoal from about 70 to about 74 Kelzan .014 6 Guar THIX .10 7 37% Formaldehyde .14 8 28~ ~mmonia .14 . .
1. Industrial Water 2. Surfactant - BASF Wyandotte Corp.
3. Anti-foam Agent - Colloids, Inc.
`4. Pocahontas Clean Coal

5. Xanthan Gum - Kelco Division, Merck & Co., Inc.

6. Guar Gum - Hercules, Inc.

7. Formaldehyde Solution - Borden Chemicals 25 8. Ammonium H~droxide - Fischer Scientific An examination of the data shows that the solids of the slurries was increased from about 71~ to 74~O by increasing the coarse fraction (-60 ~100 mesh) of the size consist from 0O to 20%.

Claims (11)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A stabilized, high solids content coal-aqueous mixture comprising particulate coal as a dis-persed solid material; water as a carrier medium; and a polyalkyleneoxide nonionic surfactant having a hydro-phobic portion and a hydrophilic portion, said hydro-philic portion comprising at least about 100 units of ethylene oxide, wherein said particulate coal has the following particle size distribution:
% weight based on mesh (Tyler Standard screen size) total dry coal -60, +100 5-20 -100,+200 15-30 -200,+325 15-30

2. The stabilized, high solids content coal-aqueous mixture of claim 1 wherein said particulate coal has the following particle size distribution:
% weight of coal mesh (Tyler Standard screen size) particle blend -60, +100 15-20 -100,+200 20-25 -200,+325 20-25

3. The stabilized, high solids content coal-aqueous mixture of claim 1 which contains a thickening agent, an antifoam agent or a viscosity stabilizer or combinations thereof.

4. The stabilized high solids content coal-aqueous mixture of claim 1 wherein the poly-alkyleneoxide nonionic surfactant has a high molecular weight of at least about 4000.

5. The stabilized, high solids content coal-aqueous mixture of claim 1 wherein the poly-alkyleneoxide nonionic surfactant comprises a composition of the formula (CH2CH2O)n-CH2-CH2-OH
wherein R is substituted or unsubstituted alkyl of from 1 to 18 carbon atoms; substituted or unsubstituted aryl or an amino group, and n is an integer of at least above 100.

6. The stabilized, high solids content coal-aqueous mixture of claim 5 wherein R is a nonyl.

7. The stabilized, high solids content coal-aqueous mixture of claim 1 wherein the polyalkyleneoxide nonionic surfactant comprises a composition of the formula HO(CH2CH2O)a{CH(CH3)CH2O]b(CH2CH2O)cH
wherein a, b and c are whole integers and a and c total at least about 100.

8. The stabilized, high solids content coal-aqueous mixture of claim 7 wherein the polyalkyleneoxide nonionic surfactant has a molecular weight of at least about 6000.

9. The stabilized, high solids content coal-aqueous mixture of claim 1 wherein the polyalkyleneoxide nonionic surfactant comprises a composition of the formula wherein R1 is an alkylene radical having 2 to 5 carbon atoms; R2 is an alkylene radical having 3 to 5 carbon atoms; a, b, c, d, e, f, g and h are whole integers and e, f, g and h total at least about 100.

10. The stabilized, high solids content coal-aqueous mixture of claim 9 wherein R1 is an alkylene radical having 2 carbon atoms and R2 is an alkylene radical having 3 carbon atoms.

11. The stabilized high solids content coal-aqueous mixture of claim 1,5 or 9 which contains an oligomeric anionic polyacrylate surfactant.